Allied Telesis AT-S63 - Manual (Page 322)

Chapter 20: Port-based and Tagged VLANs
322 Secton V: Virtual LANs
Note
Untagged ports added to a VLAN are automatically removed from
their current untagged VLAN assignment. Untagged ports removed
from a VLAN are returned to the Default_VLAN.
Removing an untagged port from the Default_VLAN without
assigning it to another VLAN leaves the port as an untagged
member of no VLAN.
The modified VLAN is now ready for network operations.
8. To permanently save your changes, select the Save Config option in
the Configuration menu.